Meeting Abstract
The first hours post-fertilization represent critical time points in teleost development, and may be an overlooked source of adult phenotypic variation. This experiment quantifies early cell stages from two killifish populations (Fundulus grandis). Killifish from a polluted area in the Houston Ship Channel are highly tolerant to environmental stressors, whereas wildtype populations outside the Houston Ship Channel are more susceptible during development. Accompanying these differences are many biochemical and physiological differences. To test the hypothesis that temperature influences these critical time points and that the responses are population-dependent, fertilized embryos from tolerant and wildtype populations were maintained in one of 22°C, 25°C, and 28°C. Repeated measures of each cleavage tracked development rate over 4 h to the 64 cell stage. Tolerant populations at 22°C in non-polluted water showed a higher (p<0.01) cleavage rate of 13.5 cleavages/h compared to the wildtype population’s rate of 13.2 cleavages/h in non-polluted water at 22°C, indicating intrinsic differences in cleavage rate associated with each population. Cleavage rate of the tolerant population to 64 cells was less temperature sensitive (Q10 = 1.8, p<0.01) then in the wildtype population (Q10 = 2.8). Alterations in physiological and morphological phenotypes associated with exposure to different temperatures indicate that temperature alters initial developmental trajectory, as expected. Unexpected was that this fundamental biological process of cell division would vary between populations. Experiments are underway to determine underlying mechanism(s) for differences in individual and interindividual cleavage rate.
